LASP sounding rocket takes a second look at the Sun

Posted June 15th, 2018

Launch (left) of the EVE sounding rocket from its flight on June 1, 2016. After the 15-minute flight, the team successfully recovered the rocket payload (shown at right with parachute). (Courtesy NASA/CU-LASP)

LASP Associate Director Tom Woods knows about space gunk.

As the principal investigator for the Extreme Ultraviolet Variability Experiment (EVE) aboard NASA’s Solar Dynamics Observatory, he’s all too familiar with the ways that exposure to the harsh space environment can lead to a spacecraft instrument’s degradation.

“Since its launch in 2010, EVE’s sensitivity has degraded by about 70 percent at some wavelengths,” Woods said.

When your job is to measure subtle variability in extreme ultraviolet, or EUV, light emitted by the Sun, that amount of degradation, left unchecked, can be a big problem.

But all is not lost: To correct for the effects of degradation, Woods uses calibration sounding rockets. The seventh such rocket is scheduled to launch on Monday, June 18, from the White Sands Missile Range in White Sands, New Mexico; The launch window opens at 1 p.m. MT.

EVE calibration sounding rockets carry a copy of the EVE instrument to approximately 180 miles above Earth, where it measures EUV light from the Sun for about 10 minutes before parachuting back down to Earth for recovery. The measurements, made by the rocket instruments unaffected by degradation, are compared to the those from the degraded satellite EVE instrument, so Woods and his team can correct for any discrepancies.

“That’s why the sounding rockets are so important—they’re like a second channel, to calibrate the channel that is seeing the Sun all the time.”

The EVE sounding rockets are a critical part of the mission. “Without the calibration, EVE wouldn’t be able to do its job,” Woods continued. “We really wouldn’t know what the brightness of the Sun is, because we wouldn’t know how much the instrument has degraded.”